Waste paper and fiber processing methods and apparatus

ABSTRACT

A method and apparatus in which fibrous waste is processed under initial over-pressure conditions is disclosed. Once the fibrous waste has been loaded into an autoclave, a compressor pressurizes the chamber, following which caustic swelling and debonding solution is injected into the chamber. In a further embodiment, a caustic solution is introduced into the fiber slurry output from an initial separation stage, following which negative pressure is maintained for a period of time chosen to enhance the desired debonding. In yet another embodiment of the present invention, de-inking solution is introduced into an initial fibrous waste processing stage which operates at super- or sub-atmospheric pressure.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of U.S. Provisional PatentApplication No. 60/183,858, filed Feb. 22, 2000, incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT N/ABACKGROUND OF THE INVENTION

[0002] A principal goal in processing waste paper is the recovery ofcellulosic fiber pulp with as little damage to the fibers as possible.If such processing damages the paper fibers to a significant degree,product made from the recovered fibers is less strong, has fewer viablecommercial uses, and consequently is of a lower economic value to theprocessor. Processing systems which result in excessively damaged fibersinclude those which mechanically break baled waste paper apart by use ofa device known as a pulper. The bale is preferably soaked in a liquidprior to pulping in order to encourage swelling of the fibers and toresult in debonding of the fibers. The soaking step decreases the degreeof fiber damage and facilitates the recovery of separated fibers, but isinconsistent in effectiveness. Often, waste paper is provided to arecycling facility in large, densely packed bales. To obtain aconsistent degree of wetness and consequent swelling and debonding underatmospheric conditions, the soaking cycle must be extended over arelatively long period of time. This leads to a requirement that afacility be capable of maintaining many bales in this soaking state foran extended period. Even given an extended soaking period, fiberswelling and debonding may not be optimal when performed at atmosphericpressure conditions.

[0003] One approach which results in an improvement over the prior artinvolves the soaking of bales under conditions of low pressure orvacuum. To achieve this, a bale of fibrous material to be recycled isloaded into a pressure vessel. Air is removed from the vessel,preferably to at least 25 inches of mercury below atmospheric pressure(−25″ Hg gage), debonding liquid such as caustic liquid is introduced tothe vessel while under vacuum conditions, followed by an optional cycleof over-pressure conditions, such as at 100 psig. The vacuum tends toextract much of the air in the bale which otherwise inhibits completedebonding liquid penetration, while the subsequent over-pressure cycleis believed to assist in the penetration of the liquid into the bale.The bale may be maintained at the over-pressure condition for a periodof time to enhance the degree of penetration, and/or the over-pressurecondition may be removed and the bale may be allowed to remain in thedebonding liquid to facilitate swelling. Subsequently, the treated baleis placed into a traditional pulper though the degree of mechanicalpulping necessary is lessened. A certain portion of the bale may beinsufficiently swollen, and may require repeated processing as before.The following U.S. Patents are believed to be representative of thejust-described processing methods and apparatus, and are incorporatedherein by reference: U.S. Pat. Nos. 5,496,439; 5,536,373; 5,271,805; and5,496,455.

[0004] The removal of ink from materials to be recycled is anotherconcern to those involved in the fiber recycling business.Uncontaminated recycled fibers can be used to produce a variety ofproducts including paper having a high degree of whiteness. However, thecost of producing such fibers can offset any financial advantage inhaving fibers which can be used for high-degree white papers.

[0005] One de-inking process is generically referred to asagglomeration, in that the ink is released from the recycled fibers andis bound up, or agglomerated, by the de-inking solution for removal fromthe pulp slurry through screening. A second de-inking process isreferred to as floatation, in which de-inking solution causing the inkto disperse as small particles. Compressed air is introduced into theslurry for agitation and for providing bubbles to which the inkparticles cling. The floating ink is then skimmed off. Typically, thede-inking liquid is introduced under atmospheric pressure conditionsinto a pulp slurry stream which is the product of a pulper as describedabove. Because such a pulper may produce fibers which are incompletelyswollen or debound, plural cycles of introducing de-inking chemical,agitating the slurry, removing the freed ink, and recovering thecontaminated de-inking chemical must be performed to produce fiberscapable of making paper having the desired degree of whiteness. Thus,the prior art process suffers from the need for repeated processing toachieve marginally acceptable results, and requires apparatusspecifically configured to enable the recovery of floating oragglomerated ink from the slurry downstream of a pulper.

BRIEF SUMMARY OF THE INVENTION

[0006] The deficiencies associated with the prior art systems andmethods described above are addressed by embodiments of the presentlydisclosed invention. One such embodiment includes an air compressor incommunication with a pressure chamber, or autoclave. Once waste paperhas been loaded into the autoclave, the compressor pressurizes thechamber, following which caustic swelling and debonding solution isinjected into the chamber. The degree of penetration of the caustic intothe waste paper is thus improved, process time is reduced, and capitalequipment expenditures are reduced. The disclosed high-pressure systemmay also include the use of an optional vacuum cycle which may beemployed to realize an initial over-pressure condition, followed by anycombination of under-pressure, ambient or over-pressure conditions.

[0007] A further embodiment of the presently disclosed invention employsone of a variety of systems for providing an initial separation offibers from either a bale of waste paper or from loose waste paper. Theoutput of the initial separation stage is then introduced into a pulperas known in the art. Subsequent to the operation of the pulper, a slurryof fiber is generated which may not be completely or adequatelydebonded. The presently disclosed system introduces a caustic solutioninto the fiber slurry, then subjects the slurry to negative pressure(s)for a period of time chosen to enhance the desired debonding. Athickener container is then employed to densify the resulting fibrousmass.

[0008] A third embodiment of the presently disclosed invention addressesthe need to remove as much ink and contaminant as possible from recycledfibers while maintaining the integrity of the fibers to the maximumdegree possible for use in recycled white paper. The system nowdisclosed enables the introduction of de-inking chemicals into apressure vessel or autoclave in which an accumulation or bale of wastepaper undergoes defibration through the use of negative pressurefollowed by optional positive pressure or through the use of positivepressure followed by optional negative pressure. De-inking solution maybe introduced subsequent to the introduction and withdrawal of causticliquid, with or without additional caustic liquid, or with the initialapplication of caustic liquid. In any permutation thereof, the wastepaper is subjected to the de-inking liquid in over- or under-pressureconditions.

[0009] It may be possible to fine-tune the parameters of the de-inkingprocess such that subsequent bleaching, through oxygen, hydrogenperoxide, or any other process, is obviated. Alternatively, bleachingmay still be required, though to a less intensive degree. Overall,however, the ultimate advancement is rooted in the introduction ofde-inking materials (e.g. agglomeration solution) into the pressurevessel under non-ambient pressure conditions.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0010] The following discussion of advancements in waste paper and fiberrecycling technology is presented in conjunction with the attachedfigures, of which:

[0011]FIG. 1 illustrates an apparatus for improved fiber recovery inwaste paper recycling;

[0012]FIG. 2 is a method of use for the apparatus of FIG.

[0013]FIG. 3 illustrates a process and apparatus for improving thedegree of fiber recovery provided by a variety of waste paper processingsystems; and

[0014]FIG. 4 illustrates an improved de-inking process and apparatustherefor.

DETAILED DESCRIPTION OF THE INVENTION

[0015]FIG. 1 illustrates an improved waste paper processing system 10according to the present disclosure. As contrasted with the prior artspecifically cited above, the presently disclosed system includes an aircompressor (“air comp.”) 12 in communication with a pressure chamber, orautoclave 14. Once the waste paper has been loaded into the autoclave14, the compressor 12 charges the autoclave 14 to a value such as oneatmosphere over ambient, or in the range of 500 psig. Caustic swellingand debonding solution 16, diluted as necessary with clean or “white”water 18, is then injected into the autoclave 14. A reservoir 20 isprovided for storing and mixing the caustic 16 and water 18 prior tointroduction into the autoclave 14. The reservoir 20 also provides areceptacle for recycled caustic solution.

[0016] The heightened pressure in the chamber 14 enhances the degree ofpenetration of the caustic 16 into the waste paper, which is preferablyand advantageously installed into the autoclave 14 in baled form. Byenabling the operation of the disclosed debonding process on baled wastepaper, additional, preliminary steps relating to the separation of thewaste paper are eliminated, thus providing a savings in terms of timeand the cost of the eliminated equipment.

[0017] In an alternative embodiment, a high-pressure pump (notillustrated) capable of delivering pressures of at least 150 psi isemployed in place of the air compressor 12.

[0018] The disclosed high-pressure system 10 may also include the use ofan optional vacuum cycle, including separator 22 and vacuum pump 24, toprovide further benefits in terms of overcoming resistance to theintroduction of caustic liquid into the bale or loose waste paper. Ifincluded, the air compressor 12 and vacuum pump 24 may be operated tovarious degrees to realize processing with an initial over-pressurecondition, followed by any combination of under-pressure, ambient orover-pressure conditions. The actual values for these conditions dependon the components used to realize the system 10, including the autoclave14 itself. A vent tank 26 is preferably provided in communication withthe autoclave 14 and the vacuum pump 24 via the separator 22 forequalizing the autoclave internal pressure with ambient.

[0019] A typical process employed by this system 10 is illustrated inFIG. 2. First, waste paper, which is typically mixed office waste (MOW),is loaded into the autoclave 14. As previously suggested, it ispreferred to be capable of processing baled waste to avoid excessivedamage to the constituent fibers by pre-processing them into a looseform and to simplify the handling of the waste.

[0020] Next, the vacuum pump 24 is employed to draw caustic solution(which may be diluted with water as required) from the reservoir 20 tothe autoclave 14. In an alternative embodiment, a pump or compressor isemployed to perform this function.

[0021] The autoclave is then pressurized by the air compressor 12 (oralternatively, the high-pressure pump, depending upon the embodiment).The specific type of waste paper, the density of the bale, the geometryof the autoclave 14, the ambient temperature, and the targeted resultsof the debonding procedure are all factors to be weighed in defining thepressure to be achieved in the autoclave 14. The desired pressurizationis then maintained for an empirically-determined period of time.

[0022] Next, the autoclave pressurization is relieved through the venttank 26, and the vacuum pump 24 is activated in order to draw down theinternal autoclave pressure. Once again, a variety of considerations gointo the determination of the target degree of vacuum. The vacuumcondition is then maintained for a beneficial and empirically-determinedperiod of time.

[0023] In one embodiment, the vacuum conditions in the autoclave arerelieved, and an over-pressure condition is re-established as describedabove. The ultimate degree of pressurization and period over which it ismaintained may be the same as previous or may differ, depending uponsome of the factors listed above.

[0024] Following over- and under-pressurization, ambient pressureconditions are re-established in the autoclave 14, and the caustic isdrained and/or recycled, as feasible. The autoclave 14 is then unloadedand the resulting mass is pulped according to one of a variety ofpulping and/or de-inking processes.

[0025] The processing of waste materials including old cardboardcontainers (OCC) and carrier stock such as six-pack carriers and milkcartons having high wet strength is believed to benefit from the use ofover-pressure first processing as enabled by the disclosed system 10.Through the use of this system 10, varying degrees of causticconcentration may be employed such that optimal performance may beachieved at ambient temperature. This is preferred in order to avoidunwanted chemical reactions which typically take place at the elevatedtemperatures sometimes employed by prior art processing systems.Processing time may also be adjusted to optimize swelling and debondingof the fibers to be recycled.

[0026] An alternative approach 30 to enhancing the efficacy of a givenpaper fiber recycling system is illustrated in FIG. 3. Here, one of avariety of systems 32 is employed for providing an initial separation or“cleaning” of fibers from either a bale of waste paper or from loosewaste paper. It should be noted that the term “waste paper” is used toinclude without limitation mixed office waste, paperboard, OCC, andother similar materials, unless otherwise specified. The cleaningprocess 32 in FIG. 3 can employ one of the negative-pressure processesspecifically identified in the patents cited and incorporated byreference in the Background section of this document, the over-pressuresystem described in conjunction with FIGS. 1 and 2 of this document, orsome other suitable system.

[0027] As a result of the operation of a typical pulper as employed inthe cleaning process 32, a slurry of fiber is generated. This isrepresented in FIG. 3 as the output of the cleaning process 32.Depending upon the fibrous material provided at the start of theprocess, the state in which it is provided, and/or the type ofprocessing system employed, incomplete swelling and debonding of fibersmay result. In some prior art systems, the incompletely separatedmaterial must be reintroduced into the start of the cleaning process,thus extending processing time and requiring a significantly largerquantity of processing materials (e.g., caustic solution and water).

[0028] It is proposed in the presently disclosed system 30 to introducea caustic solution 34 into the fiber slurry output from the cleaningprocess 32, then to subject the slurry to negative pressure(s) for aperiod of time chosen to enhance the desired debonding. A compressor orpump (not shown) may be employed for conveying the caustic into theslurry stream in a manner known to one skilled in the art. This vacuumcycle is employed to enhance the swelling of the fibers in the slurryand to facilitate the saturation of the caustic into the fibers. Thesource of caustic fluid may optionally include a reservoir 34 with asource of water for diluting the caustic to an optimal degree, similarto that shown in FIG. 1. The degree of dilution may be pre-established,or may vary, depending upon the input to or output from the cleaning ordebonding system 32.

[0029] Preferably, the disclosed system 30 provides at least two vacuumchambers 36A, 36B in order to provide a continuous system; the two ormore vacuum chambers 36A, 36B are operated in reciprocating fashion. Inthe illustrated embodiment, 150 feet of high-pressure line is utilizedfor connecting the vacuum chambers 36A, 36B to a blow tank 38, with theslurry moving at five feet per second, for a total processing time ofthirty seconds. A vacuum pump (not shown) is employed in a firstembodiment for conveying the treated slurry to the blow tank 38 while atnegative pressure. Alternatively, a pump or compressor may be employedfor the same purpose.

[0030] The blow tank 38 is employed to return the caustic slurry toatmospheric pressure. Next, a thickener container 40 is employed todensify the resulting fibrous mass by allowing the liquid medium to bedrained off; caustic recycling is an option. High density (HD) storage42 is then made available for the extracted fibrous material.

[0031] As discussed above, it is highly desirable to remove as much inkand contaminant as possible from recycled fibers, while maintaining theintegrity of the fibers to the maximum degree possible, in order toprovide fibers suitable for use in recycled white paper. In the priorart, de-inking processes have been carried out in conjunction with theoutput slurry from, for instance, a pulper. This has been preferredheretofore because prior art recycling processes have been unable tosufficiently wet a substantial portion of the material to be processedwith processing liquids prior to pulping. Rather, prior art de-inkingsystems have been employed only after fibers have been debonded out ofbaled form and into an extremely low density state in the slurry, suchas on the order of one percent fiber. Providing de-inking as a separateprocess subsequent to pulping requires additional processing equipment,materials such as suspension liquid and chemicals, and time.

[0032] To address these disadvantages, the system disclosed in FIG. 4enables the introduction of de-inking chemicals into a pressure vesselor autoclave in which an accumulation or bale of waste paper undergoesdefibration. Prior art systems would not employ de-inking chemicalsduring the defibration process because of the need to free the paperfibers through wetting followed by pulping. The presently disclosedsystem, through the use of negative pressure followed by optionalpositive pressure, as in the patents cited and incorporated by referenceabove, or through the use of positive pressure followed by optionalnegative pressure, as disclosed herein, enables more thorough saturationof the materials to be debonded. Consequently, it is now possible usingsuch systems and methods to introduce de-inking solutions into thepressure processing system. While it may be necessary, using certainpressure profiles and depending upon the materials to be processed, toperform repeated injections and withdrawals of the de-inking solutionwith or without caustic, this is still preferable in comparison with theprovision of a discrete de-inking system which operates subsequent topulping.

[0033] In one embodiment of the presently disclosed system 60, mixedoffice waste 62 is disposed in an autoclave 64, and debonding isperformed through the introduction of caustic solution from a reservoir66. After draining the caustic to waste (not shown) and/or recycling thecaustic to the reservoir 66, a de-inking solution 68 is introduced.While one or more compressors and/or pumps are employed for conveyingcaustic and de-inking solution into and out of the autoclave 64, thespecific details of such systems are considered to be within the purviewof one skilled in the relevant art.

[0034] Desirable performance has been achieved through thepressurization of the autoclave 64 immediately following theintroduction of the de-inking solution 68. However, a variety ofpermutations are possible, including the reintroduction of causticsolution 66, albeit at a lower concentration than the initial use, alongwith the de-inking solution. Similarly, the waste paper to be treatedcan be exposed to a variety of pressure profiles within the autoclaveduring the introduction of the de-inking solution 68, including positivepressure, negative pressure, or some combination thereof.

[0035] The water wash and ink recovery elements 70 illustrated in FIG. 3are conventional in a first embodiment. For instance, ink agglomerationmay be employed, whereby released and agglomerated ink is skimmed fromthe surface of the process liquids and disposed of as sludge 72.Alternatively, a proprietary wash and ink recovery system 70 may beemployed.

[0036] Additionally, the subsequent steps of pulping 74, screening 76,cleaning 78, and optional bleaching 80 may all be as known to oneskilled in the art, in one embodiment of the presently disclosed system60 and method. The treated pulp is then conveyed to storage 82. Thephysical conveyance of mixed office waste 62, caustic 66, de-inkingsolution 68, wash water 70, and resulting pulp slurry is achievedthrough means known to one skilled in the art.

[0037] Further, it may be possible to fine-tune the parameters of thede-inking process 60 such that subsequent bleaching 80, through oxygen,hydrogen peroxide, or any other process, is obviated. Alternatively,bleaching 80 may still be required, though to a less intensive degree.Overall, however, the ultimate advancement is rooted in the introductionof de-inking materials 68 (e.g., agglomeration solution) into theautoclave 64 under non-ambient pressure conditions.

[0038] Control over the equipment necessary for realizing the systems aspresently disclosed, such as automatic valves, vents, pumps, andcompressors, may be achieved through the use of automated controllers,such as a programmed computer, digital signal processor, distributedcontroller, or other computing device. Sensors utilized by suchintelligent controllers in the various embodiments of the presentlydisclosed concepts, as are familiar to those skilled in the art, includepressure sensors, temperature sensors, level sensors, pH sensors,timers, etc.

[0039] A laboratory-sized autoclave system was constructed for purposesof verifying the concepts described above. The system comprised of acylindrical pressure vessel or autoclave measuring ten inches indiameter and eighteen inches in length, fabricated from 150 psimaterials. Also used in this system were: an oil-sealed vacuum pumpcapable of delivering 27 inches Hg of vacuum; a high-pressure pumpcapable of delivering pressures up to 150 psi; an air compressor capableof delivering pressures up to 135 psi; and a reservoir tank for storingthe treatment liquor until needed for waste processing. The lab systemwas used to perform a variety of tests on mixed office waste (MOW). Ingeneral, each test comprised the following steps.

[0040] First, the vacuum pump is used to draw treatment liquor into theautoclave, a process which takes roughly 15 seconds.

[0041] Second, the autoclave is pressurized (“P1”) using thehigh-pressure pump or compressor for approximately four minutes.

[0042] Third, the increased pressure is held for a desired period oftime (“H1”).

[0043] Fourth, vacuum is applied to the autoclave while full oftreatment liquor using the vacuum pump (“wet vac”).

[0044] Fifth, the vacuum is maintained for a desired period of time(“vac hold”).

[0045] Sixth, the autoclave is pressurized again using the high-pressurepump or compressor (“P2”), a process which takes roughly four minutes.

[0046] Seventh, the pressure in the autoclave is held for a desiredperiod of time (“H2”).

[0047] Eighth, the autoclave is drained using the air compressor toforce the treatment liquor back into the reservoir tank.

[0048] The parameters for various tests are provided below in Table I,and the results of analyses of the resulting fibers are presented inTables IIA and IIB. It is worth noting that the components employed inthe laboratory test system described above and the test parameterslisted below in Table I are not necessarily indicative of specificationsto be applied to a production system. However, the results of theanalyses performed on products of the lab system are believed to provideuseful information in determining the optimal characteristics offull-scale treatment processes. TABLE I Test Test Vacuum Pressure VacPressure ID description Caustic % fill P1 device H1 Wet vac hold P2device H2 Deink 100% MOW .15% 300 mmHg 110 High 30 300 mmHg 5 110 High30 1 psi pressure sec. sec. psi pressure sec pump pump Deink 100% MOW.15% 300 mmHg 110 Air 30 300 mmHg 5 110 Air 30 2 psi comp. sec. sec. psicomp. sec Deink 100% MOW .15% 300 mmHg 110 High 30  50 mmHg 5 110 High30 3 psi pressure sec. sec. psi pressure sec pump pump Deink 100% MOW.15% 300 mmHg 110 High 30 600 mmHg 5 110 High 30 4 psi pressure sec.sec. psi pressure sec pump pump Deink 100% MOW 0 0 0 None 0 0 0 0 None 05 untreated Deink 100% MOW 0 300 mmHg 110 High 30 300 mmHg 5 110 High 306 psi pressure sec. sec. psi pressure sec pump pump Deink 100% MOW .075%300 mmHg 110 High 30 300 mmHg 5 110 High 30 7 psi pressure sec. sec. psipressure sec. pump pump Deink 100% MOW .15% in 0 0 None 0 0 0 0 None 0 8the pulper Deink 100% MOW .2% 300 mmHg 110 High 30 300 mmHg 5 110 High30 9 psi pressure sec. sec. psi pressure sec. pump pump Deink 90% white.15% 300 mmHg 110 High 30 300 mmHg 5 110 High 30 10 MOW, 10% psipressure sec. sec. psi pressure sec green MOW pump pump Deink 50% white.15% 300 mmHg 110 High 30 300 mmHg 5 110 High 30 11 MOW, 50% psipressure sec. sec. psi pressure sec. green MOW pump pump

[0049] TABLE IIA Analysis # 1 # 2 # 3 # 4 # 5 # 6 C.S. Freeness, 381 420371 358 471 313 mLs Basis weight, 62.42 62.92 62.48 63.51 64.32 64.54conditioned, g/m2 Bulk, cc/g 1.65 1.73 1.59 1.64 1.76 1.54 Burst index,2.63 2.50 2.83 2.85 2.41 3.05 kPa.m2/g Tear index, 11.6 11.3 10.2 10.811.6 9.06 mN.m2/g Tensile index, 39.8 38.3 42.6 42.2 38.1 46.9 N.m/gT.E.A., J/m2 53.8 49.3 56.9 60.7 47.5 69.6 Stretch, % 3.04 2.88 3.033.17 2.79 3.25 Brightness, 78.3 75.1 78.2 82.1 82.2 75.4 on handsheets,% Brightness, 75.9 73.3 75.4 80.5 81.4 74.0 TAPPI, re- cast, %

[0050] TABLE IIB Analysis # 7 # 8 # 9 # 10 # 11 C.S. Freeness, mLs 352437 326 333 308 Basis weight, 64.68 63.02 62.95 63.00 64.01 conditioned,g/m2 Bulk, cc/g 1.58 1.70 1.57 1.64 1.67 Burst index, 3.18 2.36 3.112.83 2.56 kPa.m2/g Tear index, 10.2 12.0 9.37 10.1 9.30 mN.m2/g Tensileindex, 48.6 38.6 48.0 42.7 39.5 N.m/g T.E.A., J/m2 76.0 47.1 66.2 62.052.4 Stretch, % 3.42 2.73 3.13 3.26 2.93 Brightness, on 80.6 72.6 79.280.9 74.3 handsheets, % Brightness, TAPPI, 78.9 72.3 77.6 76.5 66.3recast, %

[0051] These and other examples of the inventive concepts illustratedabove are intended by way of example and the actual scope of theinventive concepts are to be limited solely by the scope and spirit ofthe following claims.

What is claimed is:
 1. A method for de-inking fibrous waste, comprising:disposing the fibrous waste in a pressure vessel; introducingdefibrating solution into the pressure vessel; introducing de-inkingsolution into the pressure vessel; altering the internal pressure of thepressure vessel from ambient; returning the internal pressure of thepressure vessel to ambient; and removing, from the pressure vessel, inkreleased from the fibrous waste by action of the de-inking solution. 2.The method of claim 1, wherein the step of disposing comprises disposingfibrous waste selected from the group consisting of mixed office waste,old corrugated cardboard, carrier stock, and paperboard.
 3. The methodof claim 1, wherein the step of disposing comprises disposing thefibrous waste into the pressure vessel in baled form.
 4. The method ofclaim 1, wherein the step of introducing defibrating solution comprisesintroducing a caustic solution.
 5. The method of claim 1, wherein thesteps of introducing defibrating solution and de-inking solution occursimultaneously.
 6. The method of claim 1, wherein the step ofintroducing defibrating solution occurs prior to the step of introducingde-inking solution.
 7. The method of claim 1, wherein the step ofintroducing de-inking solution occurs prior to the step of introducingdefibrating solution.
 8. The method of claim 1, wherein the step ofaltering the internal pressure of the pressure vessel from ambientcomprises increasing the internal pressure of the pressure vessel. 9.The method of claim 1, wherein the step of altering the internalpressure of the pressure vessel from ambient comprises decreasing theinternal pressure of the pressure vessel.
 10. The method of claim 1,wherein the step of altering the internal pressure of the pressurevessel from ambient comprises sequentially increasing and decreasing theinternal pressure of the pressure vessel, each for selected timeinterval.
 11. The method of claim 1, wherein the step of altering theinternal pressure of the pressure vessel from ambient comprisesmaintaining the altered internal pressure of the pressure vessel for aselected period of time.
 12. The method of claim 1, further comprising:removing defibrated and de-inked fibrous waste from the pressure vessel;and subjecting the defibrated and de-inked fibrous waste to a mechanicalpulping process.
 13. The method of claim 12, wherein the step ofsubjecting comprises bleaching the defibrated and de-inked fibrouswaste.
 14. The method of claim 1, further comprising the step ofintroducing compressed gas into the pressure vessel to agitate thefibrous waste.
 15. An apparatus for defibrating and de-inking fibrouswaste, comprising: a pressure vessel; a source of defibrating fluid; asource of de-inking fluid; a pressure-reducing element in fluidcommunication with the pressure vessel; and a pressure-increasingelement in fluid communication with the pressure vessel.
 16. Theapparatus of claim 15, wherein the pressure vessel is adapted forreceiving the fibrous waste in baled form.
 17. The apparatus of claim15, wherein the source of defibrating fluid is a reservoir of causticliquid.
 18. The apparatus of claim 15, wherein the source of de-inkingfluid is a reservoir of de-inking liquid.
 19. The apparatus of claim 15,wherein the source of defibrating fluid and the source of de-inkingfluid are a common reservoir.
 20. The apparatus of claim 19, wherein thereservoir is adapted for receiving water for diluting the defibratingand de-inking fluids.
 21. The apparatus of claim 15, wherein thepressure-reducing element is a vacuum pump.
 22. The apparatus of claim15, wherein the pressure-increasing element is a device selected fromthe group consisting of a pump and a compressor.
 23. The apparatus ofclaim 15, further comprising a programmable controller in communicationwith and for controlling the pressure-reducing and pressure-increasingelements.
 24. The apparatus of claim 15, further comprising a pulpingsystem for pulping defibrated and de-inked fibrous waste removable fromthe pressure vessel.
 25. A method of improving the degree of defibrationin a fibrous waste slurry, comprising: introducing defibrating fluidinto the slurry; subjecting the slurry and defibrating fluid to negativepressure; conveying the slurry and defibrating fluid, while undernegative pressure, through a conduit, whereby the length of the conduitand the rate of conveyance of the slurry and defibrating fluid throughthe conduit result in a predetermined period of time during which theslurry and defibrating fluid are subject to the negative pressure. 26.The method of claim 25, further comprising introducing the slurry anddefibrating fluid, subsequent to having been subject to the negativepressure in the conduit, into a pressure-equalization vessel forenabling the slurry and defibrating fluid to be brought to substantiallyambient pressure.
 27. The method of claim 25, wherein the step ofsubjecting the slurry and defibrating fluid to negative pressurecomprises passing a first quantity of the slurry and defibrating fluidthrough a first vacuum chamber.
 28. The method of claim 27, wherein thestep of subjecting the slurry and defibrating fluid to negative pressurefurther comprises passing a second quantity of the slurry anddefibrating fluid through a second vacuum chamber operating inreciprocal fashion with the first vacuum chamber.
 29. An apparatus forimproving the degree of defibration in a fibrous waste slurry providedby a fibrous waste pulping system, comprising: a first conduit forconveying the fibrous waste slurry from the fibrous waste pulpingsystem; a source of defibrating fluid in fluid communication with thefirst conduit; a source of negative pressure in fluid communication withthe first conduit for subjecting the fibrous waste slurry anddefibrating fluid to negative pressure; a second conduit in fluidcommunication with the source of negative pressure; a pressure varyingelement for conveying the fibrous waste slurry and defibrating fluid,while under negative pressure, through the second conduit; and apressure equalization vessel in fluid communication with the secondconduit for receiving the conveyed fibrous waste slurry and defibratingfluid, and for returning the fibrous waste slurry and defibrating fluidto substantially ambient pressure.
 30. The apparatus of claim 29,further comprising a programmable controller for controlling the sourceof defibrating fluid, the source of negative pressure, and the pressurevarying element.
 31. The apparatus of claim 29, wherein the source ofnegative pressure further comprises a vacuum chamber through which thefibrous waste slurry and defibrating fluid flow.
 32. The apparatus ofclaim 29, wherein the source of negative pressure further comprisesfirst and second vacuum chambers through which the fibrous waste slurryand defibrating fluid flows in an alternating, reciprocal fashion. 33.The apparatus of claim 29, wherein the pressure varying elementcomprises a vacuum pump.
 34. The apparatus of claim 29, wherein thepressure varying element comprises an element selected from the groupconsisting of a compressor and a pump.
 35. The apparatus of claim 29,wherein the pressure equalization vessel is comprised of a blow tank.